Despite improvements and successes in therapy, cancer continues to claim the lives of numerous people worldwide. For example, colorectal cancer is the third most common cause of death from malignant disease in Western countries. Worldwide, it has been estimated there are at least half a million new cases of colorectal cancer each year.
Improvements in screening provide the opportunity to identify many individuals who have early stage cancer as well as many who do not have cancer but who are genetically predisposed to developing cancer and thus at an elevated risk of developing cancer. Moreover, because of improvements in treatment, there are numerous people who have either had cancer removed or in remission. Such people are at a risk of relapse or recurrence and so are also at an elevated risk of developing cancer.
Therapies in which T cells are isolated from a donor/individual, identified as being specific for a particular antigen, expanded ex vivo to obtain large numbers of such cell which are administered to the patient have been described. In some embodiments, the donor/individual and the patient are the same person and the cells and therapy are referred to as autologous. In some embodiments, the donor/individual and the patient are not the same person but the donor/individual is screened to identify them as having very similar combinations of alleles (matched) encoding major histocompatibility complex (MHC), classes I and II proteins, also referred to as human leukocyte antigens (HLA) and the cells and therapy are referred to as allogenic.
In addition to isolating and expanding populations of antigen-specific T cells by ex vivo culturing, the T cells may be modified after isolating and before expanding populations by having genetic material added to them that encodes proteins such as cytokines, for example IL-2.
Further, T cells may be isolated and modified by having genetic material encoding T cell receptors (TCRs) known to specifically bind to antigens. T cells may be modified by providing them with expressible forms of a T cell receptor (TCR) different from the endogenous TCR of the modified T cells. Such T cells bind to cells displaying the target of either TCR. After being modified the cells are cultured to expanded populations of exogenous-TCR expressing antigen-specific T cells by ex vivo culturing, Antigen specific TCRs and the genetic sequences that encode them may be routinely identified and isolated to produce the gene constructs used as starting material. Exogenous TCR refers to a TCR which is the product of expression of genetic material added to the cell by gene delivery techniques whether the genetic material is derived from T cells from the same individual who supplies the T cells or if the TCR coding sequences are derived from a different individual than the donor of T cell to which the TCR coding sequences are added.
To increase the number of T cells that specifically bind to the antigen, the donor may be administered a vaccine which induced an immune response in the individual that will include generation of populations of T cells in the individual that specifically bind to an antigen of the vaccine.
TCRs are membrane bound heterodimers consisting of an alpha (α) and beta (β) chain, which associate with the membrane bound CD3 protein complex and the ζ-chain (zeta chain) to form a TCR complex. The CD3 protein complex includes a CD3γ chain, a CD3δ chain, and two CD3ε chains.
Therapies are known in which immune cells isolated from a donor/individual are modified to express a fusion protein, referred to as Chimeric antigen receptor (CAR) that has an extracellular antigen binding domain and intracellular signaling domain that activates the cells. Following modification, the cells are expanded ex vivo to obtain large numbers of such cell which are administered to the patient have been described. As above, autologous refers to the donor and recipient of the cells being the same person. Allogenic refers to the donor and recipient of the cells being different people.
CAR-based immunotherapy, also referred to as T-bodies, has become an emerging modality for treating cancer. CARs are fusion receptors that comprise a domain which functions to provide HLA-independent binding of cell surface target molecules and a signaling domain that can activate host immune cells of various types, typically peripheral blood T cells, which may include populations of cells referred to cytotoxic lymphocytes, cytotoxic T lymphocytes (CTLs), Natural Killer T cells (NKT) and Natural Killer cells (NK) or helper T cells That is, while typically being introduced into T cells, genetic material encoding CARs may be added to immune cells that are not T cell such as NK cells.
Essentially, most CARs are an immunoglobulin-derived antigen binding domain fused to a T cell signaling domain such as the CD3zeta signaling chain of the T cell receptor or a T-cell costimulatory signaling (e.g. CD28) domain linked to a T-cell chain such as CD3zeta chain or the gamma-signal-transducing subunit of the Ig Fc receptor complex. CARs direct the recombinant cells in which they are expressed to bind to and, in the case of recombinant cytotoxic lymphocytes, recombinant cytotoxic T lymphocytes (CTLs), recombinant Natural Killer T cells (NKT) and recombinant Natural Killer cells (NK), kill cells displaying the antibody-specified target.
In CARs, a particularly useful form of immunoglobulin derived antigen binding domain is provided as single chain chimeric receptors that are MHC-independent. The antigen-binding domain is typically derived from an antibody and the signaling domain is derived from a TCR. In some embodiments, the CAR consists of an extracellular single chain fragment of antibody variable region that provides antigen binding function fused to a transmembrane and cytoplasmic signaling domain such as CD3zeta chain or CD28 signal domain linked to CD3zeta chain. In some embodiments the signaling domain is linked to the antigen binding domain by a spacer or hinge. When the fragment of antibody variable region binds to the antigen it specifically recognizes, the signaling domain initiates immune cell activation. These recombinant cells that express membrane bound chimeric receptors having an extracellular antibody-derived antigen binding domain and intracellular domain derived from TCRs which perform signaling functions to stimulate lymphocytes. Some embodiments provides antibody-derived antigen binding domain is a single chain variable fragment (scFv) that includes antigen binding regions of the heavy and light chain variable regions of an antibody. A signaling domain may include a T-cell costimulatory signaling (e.g. CD28) domain and T-cell triggering chain (e.g. CD3zeta).
In some embodiments, CAR coding sequences are introduced ex vivo into cells, such as T cells from peripheral lymphocytes using routine in vitro gene transfer techniques and materials such a retroviral vectors. Following gene transfer, the recombinant cells are cultured to expand the number of recombinant cells which are administered to a patient. The recombinant cells will recognize and bind to cells displaying the antigen recognized by the extracellular antibody-derived antigen binding domain.
Developments and improvements include identification of various signaling domains, the identification of various immune cells which can be used, the further modified of the cells to co-express cytokines or anti-apoptotic genes to aid in their continued survival.
There is a need for improved methods of treating individuals suffering from cancer of intestinal cells or from cancer of CNS cells. There is a need for compositions useful to treat individuals suffering from such cancers. There is a need for improved methods of preventing a recurrence of such cancer in individuals who have been treated for such cancer. There is a need for compositions useful to prevent a recurrence of such cancers in individuals who have been treated for cancer of intestinal cells. There is a need for improved methods of preventing such cancer in individuals, particularly those who have been identified as having a genetic predisposition for such cancer. There is a need for improved methods of identifying compositions useful to treat and prevent cancer of intestinal cells or CNS cells in individuals. There is a need for improved methods of treating individuals suffering from such cancers. There is a need for compositions useful to treat individuals suffering such cancer.